Automotive starter and generator armatures when assembled are not always in perfect working order and may have what are known as faults which can render them useless unless the trouble is found.
Generally there are three types of faults that can occur in armatures. They are normally identified as "open circuits" which consists of either a broken wire therein or an unsoldered connection at the commutator of an armature. A second fault is identified as "shorts" which can occur within the loops of wire which make up the armature or "shorts" within the commutator. The third fault is identified as "ground leak", which usually occurs between wire loops or commutator segments and the grounded iron laminations or steel of the armature. Finally, it must be recognized that not just one of the single faults identified above may occur, but it may be a combination of two or three of the above.
Heretofore, the only known method of detecting faults in armatures was through an instrument which required hand rotation of an armature which resulted in a laborious determination of faults. Further, the only known analyser was primitive in that to check for shorts, 60 cycles of power were passed through one-half of the coil as it lay in a cradle. A hacksaw blade is then laid on the armature and if there is vibration of the blade the armature is shorted. Also to check for opens two leads are taken from the cradled armature and moved to each contact of the commutator of the armature wherein a volt meter is read to determine whether there is a broken wire or faulty commutator connection.
As can be seen the only known prior art is very cumbersome and not particularly effective.